Rubyのソースコード読みたいやつ
・datadogのgem
https://github.com/DataDog/dd-trace-rb
・activerecord-import
https://github.com/zdennis/activerecord-import
・active-supportのcore_ext
https://github.com/rails/rails/tree/cf6ff17e9a3c6c1139040b519a341f55f0be16cf/activesupport/lib/active_support/core_ext
#読みたいやつ